How to stop drill from drifting when drilling dot and dab

[geojay]

When drilling through dot and dab into the external or party walls, I find the drill can drift quite dramatically once it hits the masonry meaning the resultant hole is in the wrong place. How can I avoid this happening? I have a battery or mains hammer drill available to me and I'll get a new bit in the morning in case that's the problem. This is a 10mm hole for use with Corefix and the house is about 13 years old (I don't know exactly what blocks are used).

 

[^woody^]

Slow speed, take the hammer off, or until it's made an impression.

 

[Koolpc]

Plus, use a smaller drill bit first, go slow into block behind. Then use the bigger drill bit...

 

[robinbanks]

(And accept that if you go through the plasterboard and end up hitting the edge of a brick, the bit is going to wander into the mortar)


Put a small bit into the battery drill and use that first

 

[oldbutnotdead]

(If your drill bit is long enough and you have the space)
Bit of scrap timber (pallet plank works) a foot long, 2 or 3 inches wide.
Drill a hole in it same dia as your masonry bit
Hold plank against wall (1 hand or a friend)
Drill through hole.
This also works using holecutters in ceilings (for downlights etc)

 

[robinbanks]

If your friend's a plank do you drill through them?

This also works using holecutters in ceilings

Good call; I'd once drilled a hole too small for a downlight but this lost my centering hole to keep steady for wrapping the smaller hole with a larger one. It kept snatching when trying to start on an angle, but zapping a hole in some scrap timber using the hole saw I wanted to use on the ceiling meant I could use the timber to hold the hole saw steady..

 

[opps]

(If your drill bit is long enough and you have the space)
Bit of scrap timber (pallet plank works) a foot long, 2 or 3 inches wide.
Drill a hole in it same dia as your masonry bit
Hold plank against wall (1 hand or a friend)
Drill through hole.
This also works using holecutters in ceilings (for downlights etc)

I use a similar process for drilling through porcelain tiles with diamond core bits. Sometimes I use a hot melt glue gun to hold the scrap of timber in place. A tap with a hammer after and the timber falls off the tiles.

Glue guns are great for those kind of jobs. A few blobs of hot melt glue will lock the timber in about 10 seconds, leaving you free to use both hands for the drilling.

 

[robinbanks]

One of my local bathroom shops uses hot melt glue to mount all the tiles in their demonstration displays; I thought it was a fantastic idea for non-service work, especially as it's possible to strip the tiles out again with little fuss and mess.